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Replace confusing is_sorted_by in format_args implementation

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This commit is contained in:
David Tolnay 2022-01-14 19:57:45 -08:00
parent abf1d94b1a
commit 1b5ff95edb
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2 changed files with 16 additions and 13 deletions
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28
compiler/rustc_builtin_macros/src/format.rs
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@ -11,9 +11,9 @@ use rustc_expand::base::{self, *};
use rustc_parse_format as parse;
use rustc_span::symbol::{sym, Ident, Symbol};
use rustc_span::{MultiSpan, Span};
use smallvec::SmallVec;
use std::borrow::Cow;
use std::cmp::Ordering;
use std::collections::hash_map::Entry;
#[derive(PartialEq)]
@ -760,21 +760,23 @@ impl<'a, 'b> Context<'a, 'b> {
// "{1} {0}"), or may have multiple entries referring to the same
// element of original_args ("{0} {0}").
//
// The following Iterator<Item = (usize, &ArgumentType)> has one item
// per element of our output slice, identifying the index of which
// element of original_args it's passing, and that argument's type.
let fmt_arg_index_and_ty = self
.arg_unique_types
.iter()
.enumerate()
.flat_map(|(i, unique_types)| unique_types.iter().map(move |ty| (i, ty)))
.chain(self.count_args.iter().map(|i| (*i, &Count)));
// The following vector has one item per element of our output slice,
// identifying the index of which element of original_args it's passing,
// and that argument's type.
let mut fmt_arg_index_and_ty = SmallVec::<[(usize, &ArgumentType); 8]>::new();
for (i, unique_types) in self.arg_unique_types.iter().enumerate() {
fmt_arg_index_and_ty.extend(unique_types.iter().map(|ty| (i, ty)));
}
fmt_arg_index_and_ty.extend(self.count_args.iter().map(|&i| (i, &Count)));
// Figure out whether there are permuted or repeated elements. If not,
// we can generate simpler code.
let nicely_ordered = fmt_arg_index_and_ty
.clone()
.is_sorted_by(|(i, _), (j, _)| (i < j).then_some(Ordering::Less));
//
// The sequence has no indices out of order or repeated if: for every
// adjacent pair of elements, the first one's index is less than the
// second one's index.
let nicely_ordered =
fmt_arg_index_and_ty.array_windows().all(|[(i, _i_ty), (j, _j_ty)]| i < j);
// We want to emit:
//

1
compiler/rustc_builtin_macros/src/lib.rs
View File

@ -2,6 +2,7 @@
//! injecting code into the crate before it is lowered to HIR.
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
#![feature(array_windows)]
#![feature(box_patterns)]
#![feature(bool_to_option)]
#![feature(crate_visibility_modifier)]